Image Positioning Correction via Corner Measurement Images
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image forming apparatuses face inaccuracies in image positioning due to measurement errors caused by individual differences in the reading apparatus, leading to trapezoidal distortion and reduced correction accuracy.
Innovation Solution
The apparatus includes a reading unit, an image forming unit, and a controller that forms measurement images on a sheet's corners, reads these images, and adjusts the image forming position based on the read data to correct for measurement errors and trapezoidal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reading apparatus scans the sheet to read the reference image for position detection, then the image forming position can be corrected, but measurement errors occur due to individual differences in the reading apparatus causing trapezoidal distortion
Solution Approach 1:
The patent applies parameter changes by detecting trapezoidal distortion characteristics (shape parameters) of the reference image and using these parameters to calculate correction amounts. The system changes the approach from direct position measurement to shape-based distortion detection, where the trapezoidal distortion parameters themselves become the basis for correction calculations, thereby compensating for reading apparatus individual differences.
Solution Approach 2:
The patent implements feedback by reading the reference image, detecting its shape characteristics, calculating the distortion amount, and then applying this distortion amount as a correction value to the image forming position. This closed-loop feedback mechanism uses the detected trapezoidal distortion as feedback information to adjust and correct the positioning, improving both measurement precision and correction reliability.
2Productivity
If the reading apparatus moves the reading part along scan rails orthogonal to the scanning direction, then the reading process is completed, but individual differences between scan rails cause different moving speeds leading to trapezoidal distortion
Solution Approach 1:
The patent converts the harmful effect of trapezoidal distortion caused by scan rail individual differences into a beneficial measurement parameter. Instead of trying to eliminate the speed differences between scan rails, the system detects the resulting trapezoidal shape of the reference image and uses this distortion pattern as useful information to calculate correction amounts, thereby improving positioning accuracy despite the speed variations.
Solution Approach 2:
The patent changes the approach from attempting to maintain uniform reading speed to accepting and measuring the speed variation parameters. By detecting the trapezoidal distortion parameters that result from different moving speeds on orthogonal scan rails, the system uses these parameters to calculate appropriate correction values, transforming a source of error into a basis for correction.
Data Source
AI summary
An image forming apparatus comprises a printer for forming an image on a sheet, an image scanner for reading a measurement image formed on a sheet, and a controller. The printer forms the measurement image at four corners of the sheet. The image scanner reads the sheet on which the measurement image is formed by dividing into two parts. The controller generates an entire read image of the sheet from the read image of the measurement image which is read by the image scanner by dividing into two parts. The controller generates an adjustment condition to adjust a position of an image formed by the printer based on the entire read image of the sheet. The controller causes the printer to form the image based on the adjustment condition.